The estimation of bone cyst volume using the Cavalieri principle on computed tomography images.

PURPOSE: To evaluate the volume of bone cyst using the planimetry method of the Cavalieri principle.

METHODS: A retrospective analysis was carried out on data from 25 computed tomography (CT) images of patients with bone cyst. The volume of the cysts was calculated by two independent observers using the planimetry method. The procedures were repeated 1 month later by each observer.

RESULTS: The overall mean volume of the bone cyst was 29.25 ± 25.86 cm3 . The mean bone cyst volumes calculated by the first observer for the first and second sessions were 29.18 ± 26.14 and 29.27 ± 26.19 cm3 , respectively. The mean bone cyst volumes calculated by the second observer for the first and second sessions were 29.32 ± 26.36 and 29.23 ± 26.36 cm3 , respectively. Statistical analysis showed no difference and high agreement between the first and second measurements of both observers. The Bland-Altman plots showed strong intraobserver and interobserver concordance in the measurement of the bone cyst volume. The mean total time necessary to obtain the cyst volume by the two observers was 5.27 ± 2.30 min.

CONCLUSION: The bone cyst of the patients can be objectively evaluated using the planimetry method of the Cavalieri principle on CT. This method showed high interobserver and intraobserver agreement. This volume measurement can be used to evaluate cyst remodeling, including complete healing and cyst recurrence.